In order to prevent a vehicle accident or the like, an occupant monitoring apparatus that monitors the physical condition of an occupant of a vehicle according to an image captured by an imaging unit may be installed in a passenger compartment.
For example, in the occupant monitoring apparatus disclosed in JP 2004-78778 A, an image of the vehicle driver's face is captured by an imaging unit configured of an image sensor (imaging element) such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). Thus, the occupant monitoring apparatus monitors the face direction according to the captured image. In addition, in the occupant monitoring apparatus disclosed in JP 2009-200718 A, an illumination unit configured of an LED (light emitting diode) projects light toward the driver's face, and an imaging unit captures an image of the driver's face. Thus, the occupant monitoring apparatus monitors the face direction and the opening and closing degree of the eyes according to the captured image. These monitoring results are output from the occupant monitoring apparatus to an ECU (electronic control unit) on a vehicle side, and are used for traveling control of the vehicle.
In the occupant monitoring apparatus disclosed in JP 2009-200718 A, the imaging unit is provided on a steering column of the vehicle, and the illumination unit is provided on a steering wheel. However, there is also an occupant monitoring apparatus in which an imaging unit and an illumination unit are installed in an identical casing. In addition, an occupant monitoring apparatus may also be installed at a place other than a steering of a vehicle.
An optical film for optically adjusting light from an occupant may be provided on an occupant side of an imaging unit. In addition, an optical film for optically adjusting light projected from an illumination unit may be provided on an occupant side of the illumination unit.
Each of JP 2017-146529 A, Domestic re-publication of PCT international application WO2014/203307, JP 2004-170696 A discloses an optical film fixing structure. In JP 2017-146529 A, an optical film is fixed to a frame with a double-sided tape, is sandwiched between a case and a casing, and is bonded to the casing. In Domestic re-publication of PCT international application WO2014/203307, an optical film is stuck on a holder curved by a tool, and then the holder detached from the tool is restored to a flat state. Thus, tension is applied on the optical film and deflection and waviness of the optical film is removed. In JP 2004-170696 A, the optical film is sandwiched between a case of a film fixing frame and a cover, then the film fixing frame is inserted into a slit provided in a casing, and thus the optical film is fixed to the casing.
In an occupant monitoring apparatus, for example, in a case where an adhesive is used to fix an optical film, it is necessary to apply and cure the adhesive. Therefore, working processes increase in number during assembly and become complicated. Further, variations in the coating amount of the adhesive or the like may cause the optical film to be distorted, which may degrade the performance of the optical film. In addition, in the case of using a double-sided tape, an adhesive property of the double-sided tape may be lowered due to changes in temperature and humidity of the surrounding environment and aged deterioration, and the optical film may be peeled off. In addition, in a case where a dedicated fixing member only for fixing the optical film is provided, the number of components increases. Thus, the working processes during assembly also increase in number and become complicated.